Population fragmentation compromises population viability, reduces a species ability to respond to climate change, and ultimately may reduce biodiversity. We studied the current state and potential causes of fragmentation in grizzly bears over approximately 1,000,000 km2 of western Canada, the northern United States (US), and southeast Alaska. We compiled much of our data from projects undertaken with a variety of research objectives including population estimation and trend, landscape fragmentation, habitat selection, vital rates, and response to human development. Our primary analytical techniques stemmed from genetic analysis of 3,134 bears, supplemented with radiotelemetry data from 792 bears. We used 15 locus microsatellite data coupled with measures of genetic distance, isolation‐by‐distance (IBD) analysis, analysis of covariance (ANCOVA), linear multiple regression, multi‐factorial correspondence analysis (to identify population divisions or fractures with no a priori assumption of group membership), and population‐assignment methods to detect individual migrants between immediately adjacent areas. These data corroborated observations of inter‐area movements from our telemetry database. In northern areas, we found a spatial genetic pattern of IBD, although there was evidence of natural fragmentation from the rugged heavily glaciated coast mountains of British Columbia (BC) and the Yukon. These results contrasted with the spatial pattern of fragmentation in more southern parts of their distribution. Near the Canada–US border area, we found extensive fragmentation that corresponded to settled mountain valleys and major highways. Genetic distances across developed valleys were elevated relative to those across undeveloped valleys in central and northern BC. In disturbed areas, most inter‐area movements detected were made by male bears, with few female migrants identified. North–south movements within mountain ranges (Mts) and across BC Highway 3 were more common than east–west movements across settled mountain valleys separating Mts. Our results suggest that relatively distinct subpopulations exist in this region, including the Cabinet, Selkirk South, and the decades‐isolated Yellowstone populations. Current movement rates do not appear sufficient to consider the subpopulations we identify along the Canada–US border as 1 inter‐breeding unit. Although we detected enough male movement to mediate gene flow, the current low rate of female movement detected among areas is insufficient to provide a demographic rescue effect between areas in the immediate future (0–15 yr). In Alberta, we found fragmentation corresponded to major east–west highways (Highways 3, 11, 16, and 43) and most inter‐area movements were made by males. Gene flow and movement rates between Alberta and BC were highest across the Continental Divide south of Highway 1 and north of Highway 16. In the central region between Highways 1 and 11, we found evidence of natural fragmentation associated with the extensive glaciers and icefields along the Continental Divide. The discontinuities that we identified would form appropriate boundaries for management units. We related sex‐specific movement rates between adjacent areas to several metrics of human use (highway traffic, settlement, and human‐caused mortality) to understand the causes of fragmentation. This analysis used data from 1,508 bears sampled over a 161,500‐km2 area in southeastern BC, western Alberta, northern Idaho, and northern Montana during 1979–2007. This area was bisected by numerous human transportation and settlement corridors of varying intensity and complexity. We used multiple linear regression and ANCOVA to document the responses of female and male bears to disturbance. Males and females both demonstrated reduced movement rates with increasing settlement and traffic. However, females reduced their movement rates dramatically when settlement increased to >20% of the fracture zone. At this same threshold, male movement declined more gradually, in response to increased traffic and further settlement. In highly settled areas (>50%), both sexes had a similar reduction in movements in response to traffic, settlement, and mortality. We documented several small bear populations with male‐only immigration, highlighting the importance of investigating sex‐specific movements. Without female connectivity, small populations are not viable over the long term. The persistence of this regional female fragmented metapopulation likely will require strategic connectivity management. We therefore recommend enhancing female connectivity among fractured areas by securing linkage‐zone habitat appropriate for female dispersal, and ensuring current large source subpopulations remain intact. The fragmentation we documented may also affect other species with similar ecological characteristics: sparse densities, slow reproduction, short male‐biased dispersal, and a susceptibility to human‐caused mortality and habitat degradation. Therefore, regional inter‐jurisdictional efforts to manage broad landscapes for inter‐area movement will likely benefit a broad spectrum of species and natural processes, particularly in light of climate change. © 2011 The Wildlife Society.

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Periodic arousal from hibernation among mammalian hibernators is poorly understood. In bats, arousal is often associated with flight. We acoustically monitored two rocky areas along the Red Deer River in southeastern Alberta for bat activity in autumn, winter, and spring months. We found bats to be active in all months and at unexpectedly cold temperatures (coldest activity –8 °C). Bats were active even when ambient temperatures remained below 0 °C during the day and night. We documented Myotis ciliolabrum (Merriam, 1886), Myotis evotis (H. Allen, 1864), and Eptesicus fuscus (Beauvois, 1796) flying outside hibernacula in winter. Active E. fuscus that we captured in mid-winter of 2004–2005 weighed less than bats captured in the fall, but masses ranged from 14.0 to 21.0 g, indicating that some individuals still had fat reserves. Captured individuals were of various ages, with a male bias. Using radiotelemetry, we located the first natural rock-crevice hibernacula for male and female E. fuscus in the Canadian prairies. Winter roosts were narrow, deep rock crevices or erosion holes located in steep valley walls. We found evidence to suggest that dehydration may be a driving force for winter flights.

A free-ranging maternity colony of big brown bats Eptesicus fuscus roosting in rock crevices along the South Saskatchewan River in south-eastern Alberta, Canada, was studied to understand better the discrepancy that exists in the literature regarding torpor use by reproductive female bats. Using radio-telemetry, thermoregulatory patterns and roost microclimate were recorded for pregnant, lactating and post-lactating females. Relative torpor use is described in several ways: the proportion of days on which torpor was used, depth, minimum body temperature, time spent in torpor, and a comprehensive torpor unit (degree-min). Pregnant and lactating female E. fuscus used torpor to the same extent overall (degree-min), but pregnant bats used torpor less frequently and with more time in deep torpor. Torpor was used to the greatest extent after weaning (post-lactation). Evidence is presented that the cost : benefit ratio for deep and prolonged periods of torpor may be highest during lactation. Microclimates of rockcrevice roosts mirrored the use of torpor throughout reproduction by bats. Lactation roosts (deeper, larger opening size) were more thermally stable and remained warmer at night compared to the shallow roosts used by pregnant and post-lactating females. It is shown that conclusions about relative use of torpor can differ depending on the units of comparison, necessitating measurement of all aspects of torpor (depth, duration and frequency). Comprehensive measurements, individual-based normothermic temperatures, and a definition of torpor that accounts for all energy savings, allow a more accurate depiction of patterns and facilitates inter-study comparisons.